Vacuum or pressure gage



(No Model.) 2 Sheets-Sheet 1. 1V[. LUSOOMB. VACUUM 0R PRESSURE GAGE.

No. 403,543. Patented May 21, 1889.

WlTNESSESI VENTUR (No Model.) 2 Sheets-Sheet 2. M. LUSOOMB. VACUUM 0RPRESSURE GAGE.

N0.'403,543. Patented Mayfil, 1889.

Fig 3.

WITNESSES: IN ENTUR ATTORNEY,

UNITED STATES PATENT OFFICE.

MARTIN LUSCCMB, OF BRIDGEPORT, CONNECTICUT.

VACUUM OR PRESSURE GAGE.

SPECIFICATION forming part of Letters Patent No. 403,543, dated May 21,1889.

Application filed January 19, 1888. Serial No 261,299. (No model.)

To all whom it may concern:

Be it known that I, MARTIN LUsooMB, a citizen of the United States,residing at Bridge port, county of Fairfield, State of Connecticut, haveinvented certain new and useful Improvements in Vacuum or PressureGages, of which the following is a specification.

My invention relates to gages in which the Bourdon tube is employed tooperate the index; and my object is to so dispose the operative parts ofthe mechanism and locate the pivots as to prevent deflection by jarringmotions, especially in the vertical direction, such as may occur to theinstrument when used on portable steam-generators or locomotives; and inorder to enable others to understand and use my said invention I willproceed to describe the construction and operation of the deviceswhereby I obtain the above results, and subsequently point out in theappended claim such characteristic features as I believe to be novel.

Referring to the accompanying drawings, forming a part of thisspecification, and in which like reference-letters indicatecorresponding parts, Figure l is a front elevation of a pressure orvacuum gage with the dial partly removed; Fig. 2, an enlarged frontelevation of the tubes and transmitting mechanism with a portion of thelatters framing structure removed; and Fig. 3, a vertical centralsection of the gage on the same scale as Fig. 2, viewed in the directionof the arrows thereon.

The supporting-frame A A for the transmitting mechanism and theindicating-tubes B B form. an independent structure projected from ananchorage, C, which is fastened to the exterior casing, D, in anysuitable manner, as by screws E, or to any other point of support,irrespective of said casing. An independent structure of the essentialparts is thereby obtained, and the whole inclosed within the usual casing, which is functionally a protector from dust and moisture, and not asupporting medium, and such fastenings of the latter, as screws throughthe flange II, that may spring the back, will not affect the interiormechanism. The back and rim of the case are integral, and the frontcomposed of glass, confined at the margin upon a felt packing, a, by thescrew-threaded rim F. The dial-plate G- is held by the lugs c on thecasing D, and is open at b, leaving the index I and its shaft freetherefrom. The frame A A is secured to the anchor C by an extremity, asA, of preferably one of its bars, the same being readily removable byscrews cl.

The semicircular indicating-tubes B B are symmetric, of equalresiliency, and directly opposite one another at their free ends,whereby such deflections as may arise by external shock will be equallyshared. The free ends of the tubes are, furthermore, located in verticalline above their fixed ends, reducing as far as possible the influenceof vertical shock.

The lever J is pivoted to the free ends of the tubes at thevertically-different points 'i j necessary to obtain a proper range ofmotion by employment of the offset-arms e, obviating the necessity ofusing tubes of unequal length, as common'in practice. The lever J isoffset to allow space for the length of the connecting-bar f beneath,and to permit its connection to the segment K at a point verticallybeneath the pivoting-points t' j.

The toothed segment K is fulcrumed by its shaft it, having hearings inthe frame A A, and the connecting-bar f operates at an adjustable radiusthereon by means of the link 70, adjusted by a set-screw, g, todetermine the proper range of movement of the index shaft relative tothat of the tubes.

The index-shaft Z bears likewise in the frame A A, projecting forward tocarry the index I. The teeth of the segment K and indexpinion on havelong bearing-surfaces, as will be observed in Fig. 3, to promotedurability.

The hair-spring or, performing the usual function of returning the indeXhand as against the action of the tubes, is anchored at 0 to the stay orstud p, which latter and the lower stay, q, unite the frame A A.

By the foregoing construction the axes of 5 all the pivotal centers ofmotion are brought approximately into a vertical plane and in operationwhen the resilient tubes are parted by a desired pressure-that is tosay, the average pressure which it is intended the gage shall carry, sayabout one hundred and twenty pounds-the segment will assume itsmid-position, being balanced thereby, as in Fig. 1. In this position thegravity of the segment is equalized on both sides of its fulcrum, andthereby free from any tendency to deflect by vertical shock. Thehorizontal movementof the free ends of the tubes as distinguished fromthe vertical, which occurs in the path they describe, is alone utilizedto perform the range of indication, and at the desired pressure thepivots ij come accurately into the common vertical plane aforesaid,being at other times approximately so, and a vertical shock to the tubeswill therefore impart no lateral movement to the lever J nor to theindex.

Witnesses:

H. F. PARKER, S. R. VAN CAMPEN, Jr.

